From: Peter Smith <smithpb2250@gmail.com>
On Thu, Sep 10, 2020 at 7:16 PM tsunakawa.takay@fujitsu.com
> <tsunakawa.takay@fujitsu.com> wrote:
> > ALTER TABLE takes long time proportional to the amount of existing data,
> while wal_level = none doesn't.
>
> Right, but if wal_level=none is considered OK for that table with
> existing data, then why not just create the table UNLOGGED in the
> first place? (or ALTER it to set UNLOGGED just one time and then leave
> it as UNLOGGED).
The target tables sometimes receive updates (for data maintenance and/or correction). They don't want those updates to
belost due to the database server crash. Unlogged tables lose their entire contents during crash recovery.
Please think like this: logging is is the norm, and unlogged operations are exceptions/hacks for some requirement of
whichthe user wants to minimize the use.
Regards
Takayuki Tsunakawa
